The invention concerns appliances for transforming electric current into diffused heat.
The pultrusion process is well known, being one that produces parts of a certain shape possessing mechanical characteristics of a high order by pulling the reinforcing materials, known as roving and mats impregnated with thermosetting resins, through a draw bench.
The most widely used kinds of roving are glass yarns laid longitudinally to the shaped parts in order to increase their resistance to bending and pulling forces.
Mats are fibrous felts, laid out in an even manner, to improve interlaminar adhesion and make the mechanical characteristics of the material produced more homogeneous.
The polymeric matrix, consisting of thermosetting resins, may be chosen, according to the use required, from a wide range of resins, such as epoxy and phenolic or others.
The form of the parts produced through a suitable draw bench can obviously be very varied, of a solid or a tubular structure.
The pultruded part can be easily processed, bored and cut with ordinary tools, and can be joined and assembled by glueing, bolting or riveting. Polymerization takes place inside the draw bench by various processes, the most common being application of heat by electric resistances or by generation of radiofrequencies.
Purpose of the above invention is to produce pultruded shaped parts which not only possess the above characteristics but also those of generating diffused heat by transformation of electric current, with a greatly improved performance as will now be explained.
Subject of the invention is a process for producing shaped parts by pultrusion that transform electric current into diffused heat.
One or more nets, made from a continuous wire of highly conductive material coated with material of high insulating capacity, are inserted in a continuous manner in the plastic material, which nets are formed in the direction of feed of the shaped part conferring electric continuity upon it from beginning to end.
The shaped part is preferably tubular.
Tube section is preferably rectangular, low in height.
Nets are applied to one of the broad sides of the shaped part.
In one type of execution there are two nets side by side.
The two nets can be joined by an intermediate net of insulating material.
Nets are made of a weft wave material and are added to the known reinforcing materials such as continuous threads of fibreglass, or roving, and felted pieces of fibreglass, known as mats.
The matrix is of thermosetting resins of unsaturated polyesters, epoxy or phenolic resin.
The nets are put on before or after the resin bath needed for pultrusion.
Added longitudinally to the nets at fixed intervals, incorporated into the shaped part, are devices for electric sockets with a groove between them lengthwise to the shaped part.
By cutting the shaped part crosswise at the position of said devices, sockets are created for connection to a source of electricity.
In one type of execution these devices consist of a small flat plate of electrically conducting material associated to a second small plate also of electrically conducting material, with a central channel facing towards the first plate, the two being associated by rivets or the like.
The socket devices are inserted at the point where the shaped part will be cut through, thus obtaining oblong panels so that after said cut, each socket device is cut to make two such devices one being integrated into one panel and the other into the next panel.
The socket devices are placed on the central axis of symmetry of the shaped part or at its sides.
Advantageously there are two nets and the socket devices are placed in pairs, each net being connected to a socket placed at one end of the panel with a second socket placed at the other end.
Advantageously the panels are connected to electric current by two heads respectively insertible at the two ends of said panel.
One head has two contacts electrically connected internally at the two channels in the two sockets and these are at one end of the panel, while the second head has two contacts, also at the position of the channels in the two sockets, these other contacts being at the other end of the panel and connected by wires to fit a plug for an external electricity socket.
Foam material is put inside the panel to increase heat insulation so that the face of the panel opposite to that holding the electrically conducting nets remains substantially cold, both because of its distance from said net and because of the interposing insulation.
The nets are continuous in the shaped part but separated in the various preferred lengths, said lengths being connected by the socket devices. At the sides of the nets, laid in one or more units on one face of the tubular shaped part, there are lateral extensions.
The shaped parts, obtained as described, make possible formation of different objects and structural bodies of innumerable forms and characteristics.
For example, the oblong panels associated side by side, with heads at their ends, can be set up to form self-carrying walls for various uses, one side being cold and the other generating diffused warmth.
Another example is that of an oven for cooking purposes or treatment of various materials with heat emitting sides, formed of a number of panels such as those described or of a more powerful kind to create even higher temperatures if needed.
An indoor room can be easily warmed by one or more panels like the above, wall or ceiling mounted with the heat generating surface towards the environment.
The invention offers evident advantages.
In addition to their high mechanical characteristics, these pultruded parts provide the further advantage of generating diffused heat by means of electric current.
The rectangular tubular form with electric nets on one of the wider sides separated from the other by insulating material, ensures optimum generation of diffused heat from one side, the other being almost completely cold.
Realization of generators of diffused heat by a long electric lead is greatly facilitated by the net formed of highly conductive material with a coating of insulation, in loops along successive rows.
Electrical continiuity is in fact assured over the whole of the generator at whatever point the cut is made on the continuous body in which the net is inserted.
All this greatly facilitates installation in any place and in any structure as no problems of electrical or heat insulation can arise.
The shaped parts obtainable with this invention not only offer important advantages on structures and in environments generally but also enormously facilitate preparation of the structures themselves associating high structural solidity to generation of heat, for greatest user comfort.